1. Field of the Invention
The present invention relates to an electric pump control system for controlling the operation of an electric pump connected to an accumulator.
2. Description of the Prior Art
There are conventionally known electric pump control systems for controlling the operation of an electric pump connected to an accumulator, which are described in Japanese Patent Application Laid-open Nos. 238770/1992 and 345568/1992.
The electric pump control system described in Japanese Patent Application Laid-open No. 238770/1992 has two series of means for detecting the pressure in the accumulator and pump driving circuits, and is capable of appropriately controlling the pump, even if one series develops a trouble.
The electric pump control system described in Japanese Patent Application Laid-open No. 345568/1992 employs both a pressure switch and a pressure sensor as means for detecting the pressure in the accumulator, and is capable of detecting troubles of these pressure detecting means.
In general, the control system using two pressure detecting means in parallel relation suffers from a problem that even if one of the pressure detecting means develops a trouble, the electric pump can be driven and stopped and hence, the trouble with one pressure detecting means cannot be easily detected. On the other hand, the control system in which only when one of the pressure detecting means is in trouble is the back-up performed by the other pressure detecting means, the following problem is encountered: only an output signal from the one pressure detecting means is used and an output signal from the other pressure detecting means is not used and for this reason, the trouble with the other pressure detecting means cannot be easily detected.